Venting Basement Toilet in same wall with Soil Stack

Asked Oct 26, 2008, 10:11 PM
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12 Answers

Hi,
I'm new to the forum, found it through googling my plumbing questions. It has helped already. Here is my question. I am confused about venting my toilet and keeping it in the path of the main drain under the slab. In other words the main stack will be dropping down the wall in essentially the same location where I would like the vent stack to run. I'm struggling figuring out all the connections for the toilet drain and vent; any assistance would be greatly appreciated. This is essentially new construction, so I have some flexibility in the location of the drain, except that it must slope left to right in this layout of the bathroom:

Good morning Gary,
You haven't given us much to work wit. Go back and draw in the main stack vent from above. How about the under slab drainage? Is it in or do you have to rough it in yourself? Where does the main run under the slab? All you've given us is a fixture lay out with no other details. No main under the slab to tie to, No stack vent coming down from above that might give us some idea where the main was located. In short go back a connect some of the "dots" for us. Back to you, Tom

Thanks for your response. This is essentially new construction. There are currently no stacks and no main drain. I want to place them such to provide the dry vents as is best practice. My only limitation is that I'd prefer the stacks in the wall as indicated and that the drain will need to run in the direction indicated. It's a clean slate that I want to do the best way possible.

I'm not sure what else I can add. Is there a more appropriate forum for new construction?
Thanks,
GaryYou did just fine Gary It would have neen nice if you had drawn in the location of the stack vent and where you think the main ran but we can work with what we have. Tom

Gary, Enclosed is how I would run your rough-in drains/vents. Red line indicate drain lines, blue dots vents for each plumbing fixtures. You can combine vents above anti-siphon level and run single vent all the way to the roof. Get back to me if you have any other question. Milo

Milo'sgiving you the UPC version which runs a vent on everything except the family dog. My code's a little more user friendly and doesn't require as many fittings. Of course if you live in California you're just out of luck.

I'm assuming then that in both codes the toilet vent then is a wet vent through the soil stack from the upper floors?

That vent behind the toilet is a stack vent with fixtures discharging from up above? This is exactly why I asked for more information in mny first post? In that case both drawings are incorrect. One of the basic mandates of both Milos and my codes are that you can not dischaqrge a major fixture past a unvented minor one. In my drawing the lavatory and in Milos drawing the down stairs toilet doesn't have its own dedicated vent. From now on I'm refusing to draw up plans based on guesswork. My fault not yours Gary. Sorry Dude! Back to square one I guess. Tom

I did not draw the soil stack because there is not a specific place that it needs to come down. That is part of my question: where should/could it go to have the best design?I had hoped the note in my drawing would have been adequate "6" wall for main vent stack and soil stack from upper floor..." Had I drawn it in, it would have forced you guys down a design path. I'm not looking for guesswork, just the best drain/vent design. I have a pretty good idea how to do it. I was just looking for a fresh approach from someone with more experience than myself, without any bias towards the design. As I said a clean slate with the givens as shown and in my original post.

In that case and if the stack behind the toilet isn't the stack vent from upstairs bring the upstairs vent down separately and take your choice of plans. Milos plan follows UPC and mine is good for the other codes in the rest of the nation. Sorry for my confusion.
Good luck, Tom

Milo, Since your code only affects 10% of the nation why don't we stop this silly code game BS and just assume that the asker lives in the other 90%. Remember what I said in my PM. Outside the box!! But since you start the bulk of your posts with, "This would be illegal in my area" It gets pretty tiresome explaining about codes. The asker certainly doesn't care unless he's pulling a permit and will be inspected and if we draw up a set of plans the Building Department doesn't like there's nothing lost. We can correct them. So enough already with UPC. Jeeze Milo! Give us a break and start posting to help the asker with his problem instead of bringing him up to your code. Tom

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